1. Field of the Invention
The present invention relates to a coil fixing device for positioning and fixing a coil to a stator core of an electric motor, and an electric motor having the coil fixing device.
2. Description of the Related Art
There are various methods for manufacturing an electric motor having a rotor and a stator. In one example, as shown in FIG. 11, a winding wire 102 is wound in a direction indicated by an arrow so as to constitute a coil 104 having a predetermined shape (which may be referred to as a unit coil), and a plurality of coils 104 are prepared. Then, as shown in FIG. 12, unit coils 104 are inserted into slots 110 of on a stator core 108 formed on an inner surface of a stator 12, and connected to each other.
In this regard, as shown in FIG. 13, when coil 104 inserted into slot 110 is not fixed by a means, coil 104 may be detached from slot 110 in an arrow direction. In order to avoid the detachment, an adhesive agent may be used. Further, as another means, Japanese Unexamined Patent Publication (Kokai) No. 2001-211592 discloses a fixing method using a wedge. Concretely, this document describes that “when wedge 5 is inserted into slot 2, as shown in FIG. 1(a), wedge 5 is inserted from above coil 3 while cut surface 51 formed by a weak line is outwardly directed. Then, by hitting a bent portion, wedge 5 becomes planar within the slot as shown in FIG. 1(b).”
When the adhesive agent is used to fix the coil, an operation thereof may be cumbersome, and components of the electric motor such as the coil may be chemically reacted with the adhesive agent. On the other hand, as another means for avoiding the detachment of the coil from the slot of the rotor core, molding inside the stator by using resin may be possible. However, even in this case, it is necessary to temporarily fix the coil by the adhesive agent, etc., until the resin is cured.
In the fixing method of Japanese Unexamined Patent Publication (Kokai) No. 2001-211592, although the adhesive agent is not used, it is necessary to form a notch in a core (or an iron core of the rotor) for holding planar wedge 5. When such a notch is formed in the core, a magnetic flux may be disturbed or distorted and the characteristic of the electric motor may be affected in an adverse way.